The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile and a composite machine thereof. The apparatus employs a two- or single-component developer to form a toner image on an image carrier through sequential repeats of charging, writing, developing, transferring and cleaning and transfers the toner image via an intermediate transfer member to a recording medium to form a colored, two-color or monochromic image thereon. The present invention also relates to a monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier in such the image forming apparatus. The present invention further relates to a toner recycling apparatus for conveying toner collected at the image carrier cleaning device to the developing device in such the monocolor image forming unit.
Conventional image forming apparatus include a type of forming a monochromatic toner image and a type of forming a multicolored, two-color toner image or colored toner image both on a recording medium such as a sheet of paper and an OHP film.
The image forming apparatus for forming a monochromatic toner image comprises one monocolor image forming unit as disclosed in Japanese Patent Application Laid-Open No. 8-248708 publication, for example. The monocolor image forming unit generally includes a developing device and an image carrier cleaning device that are located around an image carrier. Thus configured monocolor image forming unit is employed to form a monochromatic toner image on an image carrier. The toner image is then transferred from the image carrier directly to a recording medium to form an image thereon.
The image forming apparatus for forming a multicolored toner image, on the other hand, includes a type of transferring a toner image formed on an image carrier directly to a recording medium to form an image thereon. It also includes another type of transferring a toner image formed on an image carrier once to an intermediate transfer member and then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon. Among such the arrangements for forming the multicolored toner image, the former is referred to as a direct transfer type and the latter an indirect transfer type.
The image forming apparatus of the direct transfer type comprises monocolor image forming unit as disclosed in Japanese Patent Application Laid-Open No. 9-288397 publication, for example. The monocolor image forming unit includes a developing device and an image carrier cleaning device that are located around an image carrier. A plurality of such the monocolor image forming unit is arrayed along the rotary transport direction of a recording medium to provide a tandem image forming apparatus. In the tandem image forming apparatus, individual monocolor image forming unit form respective monocolor toner images, which are then transferred from individual image carriers directly to the recording medium to form a synthesized toner image thereon.
The latter image forming apparatus of the indirect transfer type employs a rotary developing device for the monocolor image forming unit as described in the above publication to form monocolor toner images sequentially on an image carrier. Thereafter, the formed monochromic toner images are transferred in turn to an intermediate transfer member to form a synthesized toner image, which is then transferred to a recording medium to form a multicolored image thereon.
Another image forming apparatus in the art has an arrangement to apply a substance for reducing a coefficient of friction on the surface of an intermediate transfer member, as disclosed in Japanese Patent Application Laid-Open No. 9-34276 publication, for example. This arrangement can achieve an increased release property between the surface of the intermediate transfer member and the toner, an improved transfer rate and a reduced cleaning load, and consequently it can prevent an after-image from occurring.
Recently, mass colored documents are handled even in an office and accordingly faster full-color printers and full-color copiers are desired increasingly more than before. A recent widespread color laser printer generally comprise a plurality of developing devices arranged touchable with one image carrier or the so-called photosensitive material. Each of different colored toner images is formed per revolution of the photosensitive material and the images are transferred in turn from the photosensitive material to an intermediate transfer member or a recording paper held on a transfer drum and the like to form a color toner image. This is the so-called one-drum type of mainstream. Among those, the intermediate transfer type as described above superimposes multicolored toner images on the intermediate transfer member and then integrally transfers them to a recording paper. To the contrary, the direct transfer type transfers them in turn to a recording paper held on the transfer drum, for example, to form a colored toner image. The direct transfer type, though it can be realized with a simple structure and low cost, is difficult to form a stable image because plural transfers to the recording paper require different conditions that depends on resistances and water contents of the recording paper. The intermediate transfer type is characterized by stability of image quality and adaptability to paper types because the image transfer to the recording paper is required only once.
To obtain a colored image with four colors, any one of the above machines is required to rotate the photosensitive material four times and therefore difficult to achieve a higher yield. To achieve a high-speed performance, through the use of increased photosensitive materials corresponding to the number of colors, and arrangement of the same number of developing devices corresponding to the photosensitive materials, a recording paper can continuously contact the photosensitive materials to obtain a colored image. This is a machine of the so-called tandem type or inline type and is commercially available. In this case, if the outer circumferential surface has a velocity equal to that of the photosensitive material in the one-drum type, it is possible to print with a speed four times higher or more than that of the one-drum type. As described above, the direct transfer type that directly transfers from the photosensitive material to the recording paper, however, cause many problems that include instability during the transfer to the recording paper and positioning during the transport of the recording paper. The so-called tandem intermediate transfer type, which employs an intermediate transfer member in a tandem system, has been proposed as is disclosed in Japanese Patent Application Laid-Open No. 59-192159 publication, for example.
FIG. 25 shows an arrangement example of the conventional one-drum intermediate transfer type that employs an intermediate transfer belt as the intermediate transfer member. In this example, there is only one transfer portion to transfer from a photosensitive material 1 to an intermediate transfer belt 3. In general, the outer circumference of the intermediate transfer belt is required to have a length at least equal to the length of a recording paper to print. Accordingly, a certain time is required for transferring an image of a second color at the same transfer portion after an image of a first color is transferred to the intermediate transfer belt 3. Therefore, if a material with a relatively higher volume resistance is employed for the intermediate transfer belt 3 and even the intermediate transfer belt 3 is charged during the transfer, there is a time margin to release the charge before a transfer is performed again.
On the other hand, in contrast to the one-drum intermediate transfer type, the tandem intermediate transfer type comprises a plurality of photosensitive materials arranged around the outer circumference of one intermediate transfer belt and a plurality of transfer portions for transferring images from the plurality of photosensitive materials. A gap between adjacent transfer portions is restricted mainly from mechanical dimensional limitations. In general, the gap between the transfer portions is set as narrow as possible so that the machine can be designed compact. Therefore, after a primary transfer from the photosensitive material to the intermediate transfer belt is performed, a time to perform a secondary transfer can be shortened. In this case, there is no time margin to release the charge generated during the primary transfer. Accordingly, the charge remaining on the surface of the intermediate transfer belt inhibits the secondary transfer. Therefore, a higher electric field is required to transfer a toner image in a good condition.
Potentials of latent images on the photosensitive material affect on the primary transfer and cause residual potential variations that reflect the potential differences. The potential variations may cause transfer variations when a solid image is transferred with a second color on the intermediate transfer belt because on the intermediate transfer belt an image-transferred portion has a transfer efficiency lower than that of a non-transferred portion. The potential variations may also produce transfer dispersions (toner scattering). The transfer dispersion unit a phenomenon that blurs an image, when a toner image is primarily transferred from the photosensitive material to the intermediate transfer belt, as a result of dispersions of the toner image that is not transferred to a correct location but dispersed to periphery thereof. Thus, the image loses its sharpness, particularly at thin line parts.
Technologies for preventing the transfer dispersions from occurring have been known. For example, Japanese Patent Application Laid-Open No. 1-282571 publication discloses a technology that erases the charges from transferred toner images by a paper-peeling charger each time a toner image is transferred to an intermediate transfer member. Japanese Patent Application Laid-Open No. 2-183276 publication discloses a technology that sets a transfer voltage at the final transfer stage higher than that at an immediately previous one and applies a certain voltage to an intermediate transfer member during a shift to each transfer stage. Japanese Patent Application Laid-Open No. 4-147170 publication discloses a technology that erases the charges from an intermediate transfer belt before transferring a toner image from the intermediate transfer member to a recording paper. Technologies disclosed in these Japanese Patent Application Laid-Open No. 1-282571, Japanese Patent Application Laid-Open No. 2-183276 and Japanese Patent Application Laid-Open No. 4-147170 publications are disadvantageous, however, because they need unit for erasing charges and unit for applying voltages as well as control unit for controlling these unit, complicating control mechanisms and preventing the devices from being down-sized.
In consideration of the above disadvantages, an application has been filed as is shown in Japanese Patent Application Laid-Open No. 10-78689 publication, which defines a length, moving speed, permittivity and volume resistivity of an intermediate transfer belt in one-drum mediate transfer system. This application, however, does not provide a consideration in the tandem intermediate transfer type.
In view of recent ecology, it is strongly desired to maintain social environments and reduce consumption of resources. Accordingly, it is publicly desired to recycle the toner for use in an image forming apparatus increasingly. The use of the recycled toner can substantially reduce an amount of toner consumption and lower a cost for maintenance.
From the above reasons, the above-described conventional image forming apparatus increasingly tends to provide the monocolor image forming unit with a toner recycling device for conveying toner collected at the image carrier cleaning device to the developing device.
In the image forming apparatus of the direct transfer type, however, even if it is either the type of forming a monochromic toner image or the type of forming a multicolor toner image, the image carrier directly contacts a recording medium. Therefore, foreign matters such as paper powders and dusts attached to the recording medium may transfer to the image carrier and the transferred foreign matters are often mixed into the toner collected at the image carrier cleaning device. The use of the toner mixed with foreign matters possibly degrades an image quality.
The image forming apparatus of the indirect transfer type, of which an image carrier does not contact directly with a recording medium, has no problem regarding the mixture of foreign matters. If the conventional configuration disclosed in Japanese Patent Application Laid-Open No. 9-288397 publication intends to recycle individual toner of each color, however, it must install image carrier cleaning devices dedicated to respective colors and mechanisms for contacting and separating the image carrier cleaning devices to and from the image carrier. Installation of such the mechanisms complicates the configuration of the image forming apparatus and therefore has a difficulty on realization.
Accordingly, the configuration, disclosed in Japanese Patent Application Laid-Open No. 9-288397 publication, is directed to recycle the black toner only.
In the image forming apparatus that prevents an after-image from occurring, for example, as shown in FIG. 24, it comprises four photosensitive materials 1 that are arranged in line to form individual monocolor toner images thereon. These toner images are sequentially transferred to an intermediate transfer member 3 by means of each of primary transfer devices 2. The image on the intermediate transfer member 3 is integrally transferred by means of a secondary transfer device 4 to a sheet s to record the image thereon. This is the so-called tandem image forming apparatus of the indirect transfer type.
Such the image forming apparatus sequentially performs transfers to the intermediate transfer member 3 in a four-time superimposing mode. Therefore, after the image transfer by the secondary transfer device 4, if an intermediate transfer member cleaning device 5 cleans the intermediate transfer member 3 on a surface, the surface can not be cleaned clearly and remains an after-image. This is a problem.
To solve the above problem, if a force to press a cleaning blade 6 of the intermediate transfer member cleaning device 5 against the intermediate transfer member 3 is increased, its surface can be degraded. This is another problem.
In the tandem intermediate transfer type, such an image forming apparatus has not been proposed, that can define the length, moving speed, permittivity and volume resistivity of the intermediate transfer belt to form an image in good condition with less transfer dispersion and low cost. This is a further problem.
A first object of the present invention is, in an image forming apparatus for forming a synthesized toner image, to prevent foreign matters from mixing into recycled toner in order to prevent an image quality from lowering and allow the recycled use of the individual toner.
A second object is, in a color image forming apparatus, to achieve the first object.
A third object is, in a color image forming apparatus, to make the best use of recycled toner that has no possibility of color-mixture.
A fourth object is, in an image forming apparatus for forming a synthesized toner image, to allow the use of recycled black toner that has less image degradation while preventing foreign matters from mixing into the recycled toner.
A fifth object is, in a color image forming apparatus, to prevent toner from degrading even if toner of different colors are mixed.
A sixth object is, in a two-color image forming apparatus, to achieve the fifth object.
A seventh object is, in a multicolor image forming apparatus with an image carrier of the drum type and an intermediate transfer member of the belt type, to achieve the first object.
An eighth object is, in a multicolor image forming apparatus with an image carrier and an intermediate transfer member both of the belt types, to achieve the first object.
A ninth object is, in an image forming apparatus for forming a synthesized toner image, to achieve the first object while improving the maintenance property.
A tenth object is, in monocolor image forming unit for use in an image forming apparatus for forming a synthesized toner image, to prevent foreign matters from mixing into recycled toner in order to prevent an image quality from lowering and allow the recycled use of individual toner.
An eleventh object is, in a toner recycling apparatus for use in an image forming apparatus for forming a synthesized toner image, to prevent foreign matters from mixing into recycled toner in order to prevent an image quality from lowering and allow the recycled use of individual toner.
A twelfth object is, in an image forming apparatus for forming a monocolor toner image, to prevent foreign matters from mixing into recycled toner in order to prevent an image quality from lowering and allow the recycled use of individual toner.
A thirteenth object is, in a monocolor image forming apparatus with an image carrier of the drum type and an intermediate transfer member of the belt or drum type, to achieve the twelfth object.
A fourteenth object is, in a monocolor image forming apparatus with an image carrier of the belt type and an intermediate transfer member of the belt or drum type, to achieve the twelfth object.
A fifteenth object is, in a monocolor image forming apparatus, to achieve the twelfth object while increasing the maintenance property.
A sixteenth object is, in monocolor image forming unit for use in a monocolor image forming apparatus, to prevent foreign matters from mixing into recycled toner in order to prevent an image quality from lowering and allow the recycled use of individual toner.
A seventeenth object is, in a toner recycling apparatus for use in a monocolor image forming apparatus, to prevent foreign matters from mixing into recycled toner in order to prevent an image quality from lowering and allow the recycled use of individual toner.
An eighteenth object is, in an image forming apparatus, to additionally prevent uncharged or insufficiently charged impurities from attaching to an image carrier in order to further prevent an image quality from lowering.
A nineteenth object is, in an image forming apparatus, to further prevent toner from being fractured frictionally in order to further prevent an image quality from lowering.
A twentieth object is, in an image forming apparatus, to further smoothen the surface feature of toner to improve a transfer rate of the toner and reduce an amount of recycled toner, thereby preventing an image quality from degrading in order to further prevent the image quality from lowering.
A twenty-first object is, in an image forming apparatus, to additionally eliminate variations in a component ratio of toner at the time of toner recycling, thereby preventing an image quality from degrading in order to further prevent the image quality from lowering.
A twenty-second object is, in an image forming apparatus, to further contact an intermediate transfer member tightly with an image carrier to improve a transfer rate of toner in order to further prevent an image quality from lowering.
A twenty-third object is to improve a cleaning performance in order to achieve the first or twelfth object while preventing an after-image from occurring without degradation of a surface of an intermediate transfer member.
A twenty-fourth object is to reduce a toner adhesion to an intermediate transfer member to improve a cleaning performance in order to achieve the first or twelfth object while preventing an after-image from occurring.
A twenty-fifth object is to increase a release property between a surface of an intermediate transfer member and toner to improve a cleaning performance in order to achieve the first or twelfth object while preventing an after-image from occurring.
A twenty-sixth object is to facilitate an increase to occur in a cleaning performance in order to achieve the first or twelfth object while easily preventing an after-image from occurring without degradation of a surface of an intermediate transfer member.
A twenty-seventh object is to define a length, surface moving speed, permittivity and volume resistivity of an intermediate transfer member in order to achieve the first or twelfth object while reducing transfer dispersions with low cost.
A twenty-eighth object of the present invention is to improve a cleaning performance in order to prevent an after-image from occurring without degradation of a surface of an intermediate transfer member.
A twenty-ninth object is to reduce a toner adhesion to an intermediate transfer member to improve a cleaning performance in order to prevent an after-image from occurring.
A thirtieth object is to increase a release property between a surface of an intermediate transfer member and toner to improve a cleaning performance in order to prevent an after-image from occurring.
A thirty-first object is to provide an image forming apparatus comprising an intermediate transfer member that can achieve the above objects.
A thirty-second object is to provide an image forming apparatus capable of facilitating an increase to occur in a cleaning performance in order to easily prevent an after-image from occurring without degradation of a surface of an intermediate transfer member.
A thirty-third object is to provide an image forming apparatus capable of further improving a cleaning performance in order to prevent an after-image from occurring without degradation of a surface of an intermediate transfer member.
A thirty-fourth object is to define a length, moving speed, permittivity and volume resistivity of an intermediate transfer member in a tandem intermediate transfer type in order to provide an image forming apparatus capable of obtaining an image in a good condition with less transfer dispersions and low cost.
To achieve the above objects, a first aspect of the present invention provides an image forming apparatus, comprising monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier, for transferring a toner image formed on the image carrier in the monocolor image forming unit once to an intermediate transfer member then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon,
wherein a plurality of the monocolor image forming unit is arrayed along the rotary transport direction of the intermediate transfer member to configure a tandem image forming device for forming a multicolor image on the intermediate transfer member, and wherein among the plurality of monocolor image forming unit contained in the tandem image forming device at least two monocolor image forming unit each include a toner recycling device for conveying toner collected at the image carrier cleaning device to the developing device.
To achieve the second object, a second aspect of the present invention provides the image forming apparatus according to the first aspect, wherein monocolor images formed by the respective monocolor image forming unit are synthesized via the intermediate transfer member to form a synthesized color image on the recording medium.
To achieve the third object, a third aspect of the present invention provides the image forming apparatus according to the second aspect, wherein in the tandem image forming device the monocolor image forming unit located upstream-most in the rotary transport direction of the intermediate transfer member includes the toner recycling device.
To achieve the fourth object, a fourth aspect of the present invention provides the image forming apparatus according to the second aspect, wherein among the plurality of monocolor image forming unit at least a black monocolor image forming unit includes the toner recycling device.
To achieve the fifth object, a fifth aspect of the present invention provides the image forming apparatus according to the second aspect, wherein in the tandem image forming device a black monocolor image forming unit is located downstream-most in the rotary transport direction of the intermediate transfer member.
To achieve the sixth object, a sixth aspect of the present invention provides the image forming apparatus according to the first aspect, wherein two monocolor image forming unit are arrayed along the rotary transport direction of the intermediate transfer member to form a two-color image on the recording medium by synthesizing via the intermediate transfer member two monocolor images formed at the two arrayed monocolor image forming unit.
To achieve the seventh object, a seventh aspect of the present invention provides the image forming apparatus according to any one of the first to sixth aspect wherein the image carrier comprises a drum and the intermediate transfer member comprises a belt.
To achieve the eighth object, an eighth aspect of the present invention provides the image forming apparatus according to any one of the first to sixth aspects, wherein the image carrier and the intermediate transfer member both comprise respective belts.
To achieve the ninth object, a ninth aspect of the present invention provides the image forming apparatus according to any one of the first to sixth aspects, further comprising a process cartridge integrally attached to and detached from a body of the image forming apparatus, wherein the process cartridge includes at least the image carrier.
To achieve the tenth object, a tenth aspect of the present invention provides a monocolor image forming apparatus, comprising monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier, for use in an image forming apparatus for transferring a toner image formed on the image carrier once to an intermediate transfer member then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon,
wherein a plurality of the monocolor image forming unit is arrayed along the rotary transport direction of the intermediate transfer member to configure a tandem image forming device for forming a multicolor image on the intermediate transfer member, and wherein among the plurality of arrayed monocolor image forming unit at least two monocolor image forming unit each include a toner recycling device for conveying toner collected at the image carrier cleaning device to the developing device.
To achieve the eleventh object, an eleventh aspect of the present invention provides a toner recycling apparatus, for use in an image forming apparatus comprising monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier for transferring a toner image formed on the image carrier in the monocolor image forming unit once to an intermediate transfer member then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon,
wherein a plurality of the monocolor image forming unit is arrayed along the rotary transport direction of the intermediate transfer member to configure a tandem image forming device for forming a multicolor image on the intermediate transfer member, and wherein among the plurality of arrayed monocolor image forming unit at least two monocolor image forming unit each include the toner recycling apparatus for conveying toner collected at the image carrier cleaning device to the developing device.
To achieve the twelfth object, a twelfth aspect of the present invention provides an image forming apparatus, comprising monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier, for transferring a toner image formed on the image carrier in the monocolor image forming unit once to an intermediate transfer member then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon,
wherein one monocolor image forming unit for forming a monochromic image on the intermediate transfer member is provided around the intermediate transfer member, and wherein the one monocolor image forming unit is provided with a toner recycling device for conveying toner collected at the image carrier cleaning device to the developing device.
To achieve the thirteenth object, a thirteenth aspect of the present invention provides the image forming apparatus according to the twelfth aspect, wherein the image carrier comprises a drum and the intermediate transfer member comprises a belt or drum.
To achieve the fourteenth object, a fourteenth aspect of the present invention provides the image forming apparatus according to the twelfth aspect, wherein the image carrier comprises a belt and the intermediate transfer member comprises a belt or drum.
To achieve the fifteenth object, a fifteenth aspect of the present invention provides the image forming apparatus according to the twelfth aspect, further comprising a process cartridge integrally attached to and detached from a body of the image forming apparatus, wherein the process cartridge includes at least the image carrier.
To achieve the sixteenth object, a sixteenth aspect of the present invention provides a monocolor image forming apparatus, comprising monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier, for use in an image forming apparatus for transferring a toner image formed on the image carrier once to an intermediate transfer member then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon,
wherein one monocolor image forming unit for forming a monochromic image on the intermediate transfer member is provided around the intermediate transfer member, and wherein the one monocolor image forming unit is provided with a toner recycling device for conveying toner collected at the image carrier cleaning device to the developing device.
To achieve the seventeenth object, a seventeenth aspect of the present invention provides a toner recycling apparatus, for use in an image forming apparatus comprising monocolor image forming unit including a developing device and an image carrier cleaning device arranged around an image carrier for transferring a toner image formed on the image carrier in the monocolor image forming unit once to an intermediate transfer member then transferring the toner image from the intermediate transfer member to a recording medium to form an image thereon,
wherein one monocolor image forming unit for forming a monochromic image on the intermediate transfer member is provided around the intermediate transfer member, and wherein the one monocolor image forming unit is provided with the toner recycling apparatus for conveying toner collected at the image carrier cleaning device to the developing device.
To achieve the eighteenth object, an eighteenth aspect of the present invention provides the image forming apparatus according to the first to twelfth aspects, wherein the image forming apparatus applies a developing bias voltage on the developing device to generate an alternative electric field at the time of development.
To achieve the nineteenth object, a nineteenth aspect of the present invention provides the image forming apparatus according to the first to twelfth aspects, wherein the image forming apparatus employs toner which contains a release agent.
To achieve the twentieth object, a twentieth aspect of the present invention provides the image forming apparatus according to the first to twelfth aspects, wherein the image forming apparatus employs toner with a roundness of 90 or more.
To achieve the twenty-first object, A twenty-first aspect of the present invention provides the image forming apparatus according to the first to twelfth aspect, wherein the image forming apparatus employs toner having a half-value width of 2.2 [fC/10 xcexcm] or less in a distribution curve of (toner charge)/(toner particle diameter).
To achieve the twenty-second object, a twenty-second aspect of the present invention provides the image forming apparatus according to the first to twelfth aspects, wherein the intermediate transfer member includes an elastic layer.
To achieve the twenty-third object, a twenty-third aspect of the present invention provides the image forming apparatus according to the first or twelfth, wherein the intermediate transfer member includes a toner adhesion reduction layer for reducing an adhesion of toner uniformly formed over a surface thereof.
To achieve the twenty-fourth object, a twenty-fourth aspect of the present invention provides the image forming apparatus according to the twenty-third aspect, wherein the toner adhesion reduction layer is composed of zinc stearate.
To achieve the twenty-fifth object, a twenty-fifth aspect of the present invention provides the image forming apparatus according to twenty-third aspect, wherein the toner adhesion reduction layer is composed of fluororesin.
To achieve the twenty-sixth object, a twenty-sixth aspect of the present invention provides the image forming apparatus according to the twenty-third aspect, wherein the toner adhesion reduction layer is composed of particles scraped off a block of bound particles using a brush and adhered to the intermediate transfer member.
To achieve the twenty-seventh object, a twenty-seventh aspect of the present invention provides the image forming apparatus according to the first or twelfth aspect, wherein the following relation is satisfied:
L0/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L0 denotes a distance in the rotary transport direction of the intermediate transfer member between a location of a charge given to a surface of the intermediate transfer member and a location of toner moved from the image carrier to the surface of the intermediate transfer member; VL, xcfx81V and xcex5 respectively denote a surface moving velocity, volume resistivity and relative permittivity of the intermediate transfer member; and xcex50 denotes the vacuum permittivity.
To achieve the twenty-seventh object, a twenty-eighth aspect of the present invention provides the image forming apparatus according to the first to twelfth aspects, wherein the following relation is satisfied:
L1/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L1 denotes the shortest distance in the rotary transport direction of the intermediate transfer member among distances between adjacent primary transfer locations, the primary transfer location being defined as a location on the intermediate transfer member to which the toner image on the image carrier to be transferred; VL, xcfx81V and xcex5 respectively denote a surface moving velocity, volume resistivity and relative permittivity of the intermediate transfer member; and xcex50 denotes the vacuum permittivity.
To achieve the twenty-seventh object, a twenty-ninth aspect of the present invention provides the image forming apparatus according to the twenty-seventh, wherein the following relation is satisfied:
L2/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L2 denotes a distance of an image carrier located downstream-most among the image carriers in the rotary transport direction of the intermediate transfer member between a primary transfer location and a secondary transfer location, the primary transfer location being defined as a location on the intermediate transfer member to which the toner image on the image carrier to be transferred, the secondary transfer location being defined as a location on the recording medium to which the toner image on the intermediate transfer member to be transferred.
To achieve the twenty-seventh object, a thirties aspect of the present invention provides the image forming apparatus according to the twenty-seventh aspect, wherein the following relation is satisfied:
L3/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L3 denotes a distance in the rotary transport direction of the intermediate transfer member between a secondary transfer location and an intermediate transfer member cleaning location, the secondary transfer location being defined as a location on the recording medium to which the toner image on the intermediate transfer member to be transferred, the intermediate transfer member cleaning location being defined as a location at which, after the transfer performed at the secondary transfer location, residual toner on the intermediate transfer member to be removed by an intermediate transfer member cleaning device.
To achieve the twenty-seventh object, a thirty-first aspect of the present invention provides the image forming apparatus according to the twenty-seventh, wherein the following relation is satisfied:
L4/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L4 denotes a distance of an image carrier located upstream-most among the image carriers in the rotary transport direction of the intermediate transfer member between a primary transfer location and an intermediate transfer member cleaning location, the primary transfer location being defined as a location on the intermediate transfer member to which the toner image on the image carrier to be transferred, the intermediate transfer member cleaning location being defined as a location at which, after the toner image on the intermediate transfer member transferred to the recording medium, residual toner on the intermediate transfer member to be removed by an intermediate transfer member cleaning device.
To achieve the twenty-eighth object, a thirty-second aspect of the present invention provides an intermediate transfer member for use in a xerography apparatus for transferring a toner image formed on an image carrier once to a surface of the intermediate transfer member then secondarily transferring the toner image from the intermediate transfer member to a sheet, wherein a toner adhesion reduction layer for reducing an adhesion of toner is uniformly formed over the surface.
To achieve the twenty-ninth object, a thirty-third aspect of the present invention provides the intermediate transfer member according to the thirty-second aspect, wherein the toner adhesion reduction layer is composed of zinc stearate.
To achieve the thirtieth object, a thirty-fourth aspect of the present invention provides the intermediate transfer member according to thirty-second, wherein the toner adhesion reduction layer is composed of fluororesin.
To achieve the thirty-first object, a thirty-fifth aspect of the present invention provides an image forming apparatus, comprising the intermediate transfer member as recited in any one of the thirty-second to thirty-fourth aspects.
To achieve the thirty-second object, a thirty-sixth aspect of the present invention provides the image forming apparatus according to the thirty-fifth aspect, wherein the toner adhesion reduction layer is composed of particles adhered on the intermediate transfer member when a block of bound particles is pressed against the intermediate transfer member while rotating the intermediate transfer member.
To achieve the thirty-third, a thirty-seventh aspect of the present invention provides the image forming apparatus according to the thirty-sixth aspect, wherein the block of bound particles is pressed with a controllable force.
To achieve the thirty-fourth aspect, a thirty-eighth aspect of the present invention provides the image forming apparatus according to the thirty-fifth aspect, wherein the following relation is satisfied:
L0/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L0 denotes a distance in the rotary transport direction of the intermediate transfer member between a location of a charge given to a surface of the intermediate transfer member and a location of toner moved from the image carrier to the surface of the intermediate transfer member; VL, xcfx81V and xcex5 respectively denote a surface moving velocity, volume resistivity and relative permittivity of the intermediate transfer member; and xcex50 denotes the vacuum permittivity.
To achieve the thirty-fourth aspect, a thirty-ninth aspect of the present invention provides the image forming apparatus according to the thirty-fifth aspect, wherein the following relation is satisfied:
L1/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L1 denotes the shortest distance in the rotary transport direction of the intermediate transfer member among distances between adjacent primary transfer locations, the primary transfer location being defined as a location on the intermediate transfer member to which the toner image on the image carrier to be transferred; VL, xcfx81V and xcex5 respectively denote a surface moving velocity, volume resistivity and relative permittivity of the intermediate transfer member; and xcex50 denotes the vacuum permittivity.
To achieve the thirty-fourth aspect, a fortieth aspect of the present invention provides the image forming apparatus according to the thirty-fifth aspect, wherein the following relation is satisfied:
L2/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L2 denotes a distance of an image carrier located downstream-most among the image carriers in the rotary transport direction of the intermediate transfer member between a primary transfer location and a secondary transfer location, the primary transfer location being defined as a location on the intermediate transfer member to which the toner image on the image carrier to be transferred, the secondary transfer location being defined as a location on the recording medium to which the toner image on the intermediate transfer member to be transferred.
To achieve the thirty-fourth aspect, a forty-first aspect of the present invention provides the image forming apparatus according to the thirty-fifth aspect, wherein the following relation is satisfied:
L3/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L3 denotes a distance in the rotary transport direction of the intermediate transfer member between a secondary transfer location and an intermediate transfer member cleaning location, the secondary transfer location being defined as a location on the recording medium to which the toner image on the intermediate transfer member to be transferred, the intermediate transfer member cleaning location being defined as a location at which, after the transfer performed at the secondary transfer location, residual toner on the intermediate transfer member to be removed by an intermediate transfer member cleaning device.
To achieve the thirty-fourth aspect, a forty-second aspect of the present invention provides the image forming apparatus according to thirty-fifth aspect, wherein the following relation is satisfied:
L4/VL greater than xcfx81Vxc2x7xcex5xc2x7xcex50
where L4 denotes a distance of an image carrier located upstream-most among the image carriers in the rotary transport direction of the intermediate transfer member between a primary transfer location and an intermediate transfer member cleaning location, the primary transfer location being defined as a location on the intermediate transfer member to which the toner image on the image carrier to be transferred, the intermediate transfer member cleaning location being defined as a location at which, after the toner image on the intermediate transfer member transferred to the recording medium, residual toner on the intermediate transfer member to be removed by an intermediate transfer member cleaning device.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.